PROJECT SUMMARY/ABSTRACT Plants have been used to treat illnesses since antiquity, with the first documented case of this practice dating back more than 4,000 years. Botanical medicines are still a major form of healthcare around the world, and in the US are widely used in the form of herbal dietary supplements. The immense chemical complexity and variability of plant based (botanical) medicines makes evaluation of their safety and efficacy extremely challenging. Much of the research in the field of botanical natural products has been focused on reducing this complexity in pursuit of single active compounds that can be developed as pharmaceutical drugs. However, traditional and modern alternative health care practices typically employ botanical medicines as complex mixtures. There is ample literature precedent that the overall biological effect of a mixture can be the result of multiple constituents, which together exert ?combination effects,? acting synergistically or antagonistically. Specific to this proposal, we have shown that the antimicrobial activity of the traditional Chinese medicine Salvia miltiorrhiza (Chinese red sage or danshen) cannot be fully explained by widely used partial least squares (PLS) methods of modeling biological data. We hypothesize that discrepancies between the observed and predicted biological activity data are due to synergistic or antagonistic interactions among compounds present in the extract. To test this hypothesis, we will develop a novel approach that will more effectively model the data by accounting for synergistic and antagonistic interactions among constituents. The proposed approach will combine traditional natural products based isolation with metabolomics and bioinformatics, enabling a more comprehensive understanding of mixture behavior than is currently possible. As an outcome of these studies, we propose to identify combinations of chemical constituents from S. miltiorrhiza that together exert synergistic, additive, or antagonistic antimicrobial activity. More broadly, we expect to demonstrate new methodologies that can be adopted by other investigators studying biologically active mixtures. Importantly, these studies will be conducted with major involvement from graduate and undergraduate students, who will participate in interdisciplinary research at the intersection of chemistry, microbiology, and bioinformactics. The PI for this proposal has an exceptional track record for preparing students (particularly women and underrepresented minorities) for careers in the biomedical sciences, and has mentored 88 students in research since 2001.